RELATIONSHIP BETWEEN EXPRESSION OF INTEGRINS AND GRANULOSA-CELL APOPTOSIS IN OVARIAN FOLLICLES OF THE MARMOSET (CALLITHRIX-JACCHUS)

DNA fragmentation (apoptosis) was studied during the follicular, perio vulatory and luteal phase in the marmoset monkey ovary by means of ter minal transferase mediated in situ nick end labeling, and correlated w ith immunohistochemical localization of integrins (beta 1, alpha 2 and alpha 6 subunits). For this purpose a double-labeling technique was d eveloped, During all phases, apoptosis of granulosa cells was exclusiv ely restricted to tertiary follicles displaying advanced stages of atr esia (as morphologically determined). During early stages of atresia i n tertiary follicles, indicated by widened intercellular spaces, no ap optosis was seen, Staining intensities for integrins beta 1 and alpha 6 were strong in intact primordial/primary, secondary and tertiary fol licles. Integrin expression of granulosa cells was weak in atretic ter tiary follicles but not in atretic primary or secondary follicles. Dou ble labeling revealed that DNA fragmentation was solely found in granu losa cells of tertiary follicles displaying faint or absent staining f or both integrin subunits. During the periovulatory and the luteal pha se, granulosa cells of atretic tertiary follicles bordering on the bas al membrane, which were referred to as luteinizing cells, expressed th e beta 1 subunit as well as the alpha 2-integrin subunit whereas granu losa cells neighboring to the antrum were apoptotic and negative for i ntegrin immunoreactivity. In summary, early atresia of tertiary follic les is first characterized by morphological alterations as wide interc ellular gaps, without any signs of granulosa cell apoptosis. Advanced stages of atresia, in tertiary follicles however, are accompanied by a poptosis of granulosa cells and a faint or absent staining for integri n subunits beta 1 and alpha 6. According to recent in vitro findings, our results point to a possible relation between granulosa cell apopto sis of tertiary follicles and integrin expression in ovarian marmoset follicles.